So-called milling is performed on an object that is made of a metal material to form a flat surface. Milling is a processing method for an object to be cut (work) into a flat shape by rotating a cutting tool such as an end mill, a face mill, a plunger, a drill or the like that is fixed to a main spindle (rotating shaft) at high speed.
A material such as a titanium (Ti) is a material having excellent corrosion resistance, heat resistance and strength, however, for that reason, is classified as a material that is difficult to cut, and when milling is attempted, cutting requires time and invites early wear of the cutting tool. Therefore, processing to improve the cutting efficiency is performed by irradiating the site on an object to be cut where cutting will be performed (preset cutting site) with a laser beforehand, and heating that preset cutting site. Japanese Laid-open Patent Publication No. 2003-19615, for example, discloses technology wherein at the same time that milling is performed, the cutting cross-section surface is heated using a laser a few millimeters ahead of the current cutting location.
However, in the technology disclosed in Japanese Patent Application No. 2003-19615, because the positional relationship between the cutting tool and the laser device is fixed, the areas that are shaded by the cutting tool are created and these areas cannot be physically irradiated by the laser, and thus causing a problem of the cutting efficiency and inconvenience.